问如何在MS BOT框架sdk4中启用介绍消息的文本到语音服务

EN

<script>
    // Must create store so we can send command
    const store = window.WebChat.createStore();
    window.WebChat.renderWebChat({
    directLine: window.WebChat.createDirectLine({ secret: 'YourBotSecret' }),
        // Add speech capability
        webSpeechPonyfillFactory: window.WebChat.createBrowserWebSpeechPonyfillFactory(),
        store
    }, document.getElementById('webchat'));

    document.querySelector('#webchat > *').focus();

    // When mic button is clicked, send message as though user has spoken
    // Note: 'test' will not be displayed at all to the user. You can replace it with anything.
    document.querySelector('[title="Speak"]').addEventListener('click', () => {
    store.dispatch({
        type: 'WEB_CHAT/START_SPEAKING',
        payload: { text: 'test' }
    });
    });

    // Programatically click the mic button
    document.querySelector('[title="Speak"]').click();

    // Programatically click the mic button back off
    window.setTimeout(() => document.querySelector('[title="Speak"]').click(), 500);

    // Stop listening
    document.querySelector('[title="Speak"]').removeEventListener('click', () => {
    store.dispatch({
        type: 'WEB_CHAT/START_SPEAKING',
        payload: { text: 'test' }
    });
    });
</script>